1. Technical Field
The present invention relates to frequency multipliers and, more particularly, to frequency quadruplers that operate at millimeter-wave frequencies.
2. Description of the Related Art
Frequency multipliers are important components in millimeter-wave (mmWave) data communication, radar, and imaging systems. Frequency multipliers often need filtering structures to reject the fundamental component of a signal and any other unwanted components. Since it is hard to generate output power at high frequencies, particularly at mmWave frequencies, power combining structures may be used to add the power from individual sources. However, both filters and power combiners increase the frequency multiplier's surface area on a chip and introduce substantial losses in the output signal path.